This collection contains mostly entomological material, with much information on the description and identification of particular insects, entomological collections, and the study of entomology in Europe and the United States. In addition, there are materials on medicine and hospitals during the American Civil War, on the Corps of Topographical Engineers, the United States Army, on natural history in the United States, and on the LeConte's family. Some letters are written to President Rutherford B. Hayes and concern the Commissionership of Agriculture, for which LeConte was considered, but not appointed. Letters of John Eatton LeConte and Joseph LeConte are included.

A miscellaneous collection of letters, mainly of English scientists, written to various people. There are mostly one or two letters, except for those of John Peter Gassiot, William Huggins, Edwin R. Lankester, James Mackintosh, David Prain, and William Whewell.

Benjamin Silliman (1779-1864, APS 1805) was a scientist and educator. As a professor of chemistry at Yale University from 1802 to 1853, and pioneering teacher of chemistry, mineralogy and geology, Silliman was largely responsible for the conversion of Yale College to Yale University, with strong medical and scientific departments.

The collection of about 850 items covers the period from 1782 to c. 1936, with the bulk dating to the 1780s to 1840s. The collection is divided into four series. Series I contains correspondence relating to a wide variety of topics, including French and English politics, business, trade, religious matters, and personal affairs. Many of the items are letters of introduction. There is also information on John Vaughan's immigration to America, Joseph Priestley, vaccines and inoculation (with Jefferson's comments on the same), Vaughan's business in Philadelphia, and the American Philosophical Society. Also included in this series are 2 boxes with copies of Vaughan correspondence as well as miscellaneous notes by E. W. Madeira, gathered in the course of his research on Vaughan in the 1930s. Series II consists of three volumes. Included are two of Vaughan's commonplace books. One, entitled, "J. Vaughan's book," May 17, 1779 (47 pp., in Latin; 870/L34), includes mostly Latin notations. The other commonplace book, dated 1783 (ca. 66 pp.; B V 462.c), includes comments on several prominent Americans, such as Benjamin Rush and David Rittenhouse, as well as American society generally. The third volume is a copybook with thirty letters spanning the period 1784 to 1801 (B V462.1). Series III includes material relating to Vaughan's administration of the estate of the Philadelphia merchant Samuel Merrick, 1796-1822 (Vaughan-Merrick Papers, B V462.m; 2 boxes). Series IV consists of correspondence between Vaughan and the DuPont Co. for which he served as agent (B V462.4; photocopies of 73 letters).

Founded in 1743 by Benjamin Franklin, the American Philosophical Society was the first learned society in the United States. For over 250 years, the Society has played an important role in American cultural and intellectual life. Until the mid-nineteenth century, the Society fulfilled the role of a national academy of science, national library and museum, and even patent office. Early members of the Society included Thomas Jefferson, David Rittenhouse, Benjamin Rush, Stephen Peter Du Ponceau, George Washington, and many other figures prominent in American history. The Archives of the American Philosophical Society consists of 192.25 linear feet of material, organized into thirteen record groups dating back to 1743. The Society's archives extensively documents not only the organization's historical development but also its role in American history and the history of science and technology.

The Thomas Jefferson papers contain a large number of correspondence both to and from Jefferson, as well as various other material related to American Revolutionary War and Early Republic. Includes correspondence with Patrick Henry, Charles Willson Peale, Richard Henry Lee, Horatio Gates, David Rittenhouse, Robert Patterson

These papers reflect Isaac Hays' interests and activities in the medical profession and as an editor. His interest in paleontology, especially in the controversy with G. W. Featherstonhaugh, is also represented. There is one separate volume (77 letters) containing correspondence about natural history and naturalists, written to Hays by C. L. Bonaparte, George Ord, Thomas Say, and Charles A. Lesueur. The correspondence in the larger collection, however, contains much material on the American Journal of the Medical Sciences, particularly illuminated in the correspondence with John D. Godman. The I. Minis Hays material consists of letters from doctors, relating to medicine and medical publications and editing, as well as medical organizations. Most significant of the correspondence is that with John Shaw Billings (ca. 60 letters).

This is a collection of letters, letterbooks, account books, scrapbooks, etc., concerning the families of Robert Hare and Thomas Willing. The letters and other documents include early family material, as well as documents written by numerous family relations, and some obviously only collected by them. The Willing family letters (1744-1901) are diverse, concerning family matters, business, society, comments on the Civil War, etc. There are numerous letters from Thomas Willing, many concerning his banking career, as President of the Bank of North America and later at the first Bank of the U.S. The Hare family letters (1724-1965) are more extensive and diverse, including much on travel in the U.S. and elsewhere. There is a letter from Robert Hare Jr. concerning steam engines, and letters from Horace Binney Hare concerning his education at Harvard, 1860, his trip to San Francisco and the west, 1862, and numerous letters written while a soldier in the Civil War. There are many letters from Horace Binney (1780-1875, DAB) to his daughter Esther, who was married to John Innes Clark Hare (1816-1905, DAB), concerning family travel and court cases. There are also letters from outside the family, such as those from Dorothea L. Dix. The bound volumes include, among others: Robert Hare letterbooks (1824-1825, 1841-1857), estate records, and laboratory expense accounts (1818-1860); G. H. Hare's journal or log of cruises aboard the U.S. United States (1841) and U.S. Flint (1845); Horace Binney Hare's 1862 journal of his trip to San Francisco. There are account books and accounts (1754-1795) kept by Thomas Willing; accounts of the controversy over the estate of John Innes Clark; and records of the First Colored Wesley Methodist Church of Philadelphia (receipt book, 1820-1848; minute book, 1827-1844). There are also Philadelphia court records, and minutes of the Common Council of the city, 1832.